Coloring can be applied to the surface of contact lens to alter the coloring of the eyes of the person wearing the lens. The coloring of the pupil of the human eye is, however, very complex. The center of the pupil has a deep, almost black, solid color, while the outer periphery of the pupil has a lighter, distinguishable color such as brown, hazel, blue, green, or some blend thereof. The outer periphery of the pupil, however, is not uniform in color. It may be deeper near the outer edges of the pupil than near the center, and the coloring may be a composition with a background of one color broken by fine lines of a second color which extend radially inward from the outer circumference of the pupil. A combination of three or four colors, therefore, may be required to duplicate the coloring of the human eye. To print coloring on a contact lens which, when fitted into the eyes of a wearer, will change the coloring of the eyes of the wearer and not appear to be unnatural, must have a pattern of colors printed on the surface thereof which duplicates the pattern of the human eye.
To print a pattern having a plurality of colors onto a contact lens, the pattern must be broken down into subpatterns, with each subpattern corresponding to one of the colors which make up all of the colors in the pattern. The subpatterns must be aligned such that the printing of ink of one color does not overlay upon the ink of another color, because the multiple layering of the inks will create an uneven surface which can cause irritation in the eye of the wearer, and it will give an unnatural coloring to the pattern. Both of these consequences reduce the desirability of the contact lens to which the coloring has been applied.
Machines are currently available which apply a plurality of subpatterns of color to a contact lens and these machines use a carousal having a plurality of retainers thereon for retaining a lens. As the carousal rotates each lens retainer is moved from one coloring station to another with the pattern for a different coloring applied at each coloring station. Each of the stations includes a vertically moveable print pad and a first assembly for applying a subpattern of fresh ink to the print pad before the print pad is pressed against a contact lens and a second assembly for removing residue ink from the print pad after the pad has been used to apply ink to a contact lens. Each first assembly has an image die with a pattern therein which is moveable, or "doctored," to a first position at which ink is applied into the pattern of the die after which it is doctored to a second position below the print pad. The print pad is lowered and compressed against the image die and thereafter elevated, after which the ink from the image die is retained on the print pad. The image die is doctored back to the first position at which ink is reapplied. With the image die doctored out from under the print pad, the carousal can be rotated to move the lens retainer with a contact lens thereon beneath the print pad and the print pad is again lowered to apply ink to the surface of the contact lens. After the print pad is again raised, an incremental rotation of the carousal will then move the retainer and contact with printed material thereon towards its next stage. Residue ink on the print pad is removed by the movement of a cleaning table retaining a section of a three inch wide cellophane tape below the print pad and lowering the print pad against the adhesive of the tape. When the print pad is raised the role of cellophane tape is incrementally advanced to position a clean section of tape on the table and the cleaning table is moved out from below the print pad. The cycle is then repeated with the print pad moved downwardly for brief intervals to receive ink from the image die, to apply the ink to a contact lens, and to contact the adhesive of the tape to remove excess ink from the surface thereof.
Machines as described above will produce high quality colored lens with patterns printed thereon which duplicate the appearance of the pupil of the human eye, although such machines do have limitations. First, there are practical limitations to the size of the carousal and therefore there are limitations to the number of lens which can be simultaneously printed by such machines. Second, by the nature of their circular configuration, the machines have substantial space requirements. Third, the machine moves one of the three elements of image die, cleaning table, and contact lens container successively below the print pad and the speed at which the machine operates is limited by the speed at which the elements can be successively first moved under the print pad, and then be removed therefrom. It would therefore be desirable to provide a machine for applying multiple colors to contact lens which could carry out the steps of the printing process more rapidly to thereby provide a faster operating machine. Furthermore, it would be desirable to provide a machine having more economical space requirements such that more machines could be placed within a work site and thereby provide for increased productivity of a work site of a given size.